ORIGINAL ARTICLE: Expression of the Small Heat Shock Protein alphaB-Crystallin in Term Human Placenta

The effect of heat shock protein 27 on extravillous trophoblast differentiation and on eukaryotic translation initiation factor 4E expression

Heat shock protein (HSP27) is expressed in human placentae. Previously, we showed that HSP27 is expressed in the villous cell column of first trimester placental explants and in extravillous trophoblast (EVT) cells. EVT differentiation is accompanied by increased motility, matrix metalloproteinase (MMP) activity, decreased proliferation and expression of specific markers such as HLAG and CD9. HSP27 regulates cell apoptosis, migration, protein stability and the availability of eukaryotic translation initiation factors, such as eukaryotic translation initiation factor 4E (eIF4E). eIF4E supports trophoblast cell proliferation and survival. We wanted to explore the effect of HSP27 silencing on trophoblast cell phenotype, EVT markers and eIF4E expression and regulators [4E-binding protein (4E-BP1) and MAP kinase-interacting kinase (MNK1)]. This study evaluated the effect of HSP27 siRNA on placental explant and HTR-8/SVneo migration, MMP activity/mRNA, cell death, cell cycle, HLAG/CD9 levels, and eIF4E and its regulators' total and phosphorylated levels. Furthermore, we evaluated HSP27 levels in placentae exposed to ribavirin, which triggers EVT differentiation. We found that HSP27 silencing increased cell death in HTR-8/SVneo and placental explants. Furthermore, it reduced HTR-8/SVneo migration and EVT outgrowth from the explants (P < 0.05), MMP2 activity and expression of EVT markers HLAG and CD9 (in placental explants and HTR-8/SVneo, respectively, P < 0.05). Induction of EVT differentiation by ribavirin elevated HSP27 levels. Finally, HSP27 silencing in both HTR-8/SVneo and placental explants reduced eIF4E levels (33 and 28%, respectively, P < 0.05) and the levels of its regulators 4E-BP1 and MNK1 (37 and 32%, respectively, done on HTR-8/SVneo only), but not their phosphorylated forms. Altogether, our results suggest that HSP27 contributes to EVT cell differentiation.

Expression and clinical significance of SHP2 in gastric cancer

OBJECTIVES

To investigate the expression and clinical significance of the protein tyrosine phosphatase, nonreceptor type 11 (PTPN11 or SHP2) gene, which encodes Src homology 2 domain-containing phosphatase (SHP-2) in gastric cancer.

METHODS

SHP2 expression was detected by immunohistochemical staining and real-time quantitative reverse transcription-polymerase chain reaction in tissue samples of normal gastric mucosa and different grades of gastric cancer. Correlation between SHP2 expression and standard clinico pathological parameters was analysed.

RESULTS

Immunohistochemical staining revealed significantly higher rates of SHP2 expression in gastric cancer tissues (72.5%) versus normal gastric mucosa (21.9%). SHP-2 mRNA levels were also significantly higher in gastric cancer tissues versus normal gastric mucosa. SHP2 expression correlated significantly with tumour differentiation, clinical classification and lymph node metastases, but was independent of sex and age.

CONCLUSIONS

SHP-2 is upregulated in gastric cancer and may be related to the development of gastric cancer. SHP-2 may be a potential prognostic marker of, or a therapeutic target for, gastric cancer.

Differential expression and regulation of Cryab in mouse uterus during preimplantation period

The aim of this study was to examine the expression and regulation of the crystallin, alpha B (Cryab) gene in mouse uterus during the peri-implantation period by in situ hybridization and real-time PCR. There was no detectable Cryab mRNA signal on days 1-4 of pregnancy. On day 5 of pregnancy when embryo implanted, a high level of Cryab mRNA signal was found in the subluminal stroma surrounding the implanting blastocyst. On days 6-8, Cryab mRNA was strongly expressed in the primary decidua. By real-time PCR, a high level of Cryab expression was detected on days 7 and 8 of pregnancy, although Cryab expression was seen from days 1 to 8. Under in vivo and in vitro artificial decidualization, Cryab expression was significantly elevated. Compared with the progesterone-primed delayed implantation uterus, a high level of Cryab mRNA expression was observed in estrogen-activated implantation uterus. In the uterine stromal cells, cAMP, estrogen, and progesterone could induce the expression of Cryab gene. In the ovariectomized mouse uterus, estrogen could also induce the expression of Cryab while progesterone inhibited its expression. Our data suggest that Cryab may play an important role during mouse embryo implantation and decidualization and that estrogen and progesterone can regulate the expression of Cryab gene.

Enhancement of invasion of hepatocellular carcinoma cells through lysophosphatidic acid receptor

OBJECTIVES

Lysophosphatidic acid (LPA) is a bioactive lipid mediator involved in tumour progression, cell invasion and metastasis. The mechanism of action of LPA in the invasive and metastatic capacity of human hepatocellular carcinoma (HCC) is not fully understood. This study investigated the effects of LPA on HCC cell invasion and induction of matrix metalloproteinase (MMP) -2 and -9.

METHODS

LPA receptor levels in HCC cell lines were detected by Western blot analysis; HCC cell invasion was analysed by the Transwell® system. The LPA receptor blocker Ki16425 was used to determine whether HCC cell invasion was LPA dependent. Expression of the MMP2 and MMP9 genes in HCC cells was determined by real-time quantitative reverse transcription-polymerase chain reaction (qPCR).

RESULTS

LPA increased HCC cell invasion, which was LPA-receptor dependent. Real-time RT-qPCR showed that LPA increased MMP9, but not MMP2, expression in HCC cells. Pharmacological inhibition of LPA receptors with Ki16452 significantly attenuated LPA-induced HCC cell invasion.

CONCLUSIONS

HCC invasiveness is facilitated by LPA and may be relevant to tumour progression. Thus, LPA receptors may be a potential therapeutic target for HCC.

Regulation of early trophoblast differentiation - lessons from the mouse

The earliest stages of trophoblast differentiation are of tremendous importance to mediate implantation and to lay the anatomical foundations for normal placental development and function throughout gestation. Yet our molecular insights into these early developmental processes in humans have been limited by the inaccessibility of material and the unavailability of trophoblast cell lines that fully recapitulate the behaviour of early placental trophoblast. In this review we highlight recent advances that have come from the study of distinct stem cell types representative of the embryonic and extraembryonic lineages in the mouse, and from the study of mouse mutants. These models have revealed the presence of intricate transcriptional networks that are set up by signalling pathways, translating extracellular growth factor and cell positional information into distinct lineage-specific transcriptional programmes. The trophoblast specificity of these networks is ensured by epigenetic mechanisms including DNA methylation and histone modifications that complement each other to define trophoblast cell fate and differentiation. Despite the anatomical differences between mouse and human placentas, it seems that important aspects of early trophoblast specification are conserved between both species. Thus we may be able to build on our insights from the mouse to better understand early trophoblast differentiation in the human conceptus which is important for improving assisted reproductive technologies and may enable us in the future to derive human trophoblast stem cell lines. These advances will facilitate the investigation of genetic, epigenetic and environmental influences on early trophoblast differentiation in normal as well as in pathological conditions.

ELF5-enforced transcriptional networks define an epigenetically regulated trophoblast stem cell compartment in the human placenta

The first definitive cell fate decision in development occurs at the blastocyst stage with establishment of the trophoblast and embryonic cell lineages. In the mouse, lineage commitment is achieved by epigenetic regulation of a critical gatekeeper gene, the transcription factor Elf5, that reinforces placental cell fate and is necessary for trophoblast stem (TS) cell self-renewal. In humans, however, the epigenetic lineage boundary seems to be less stringent since human embryonic stem (ES) cells, unlike their murine counterparts, harbour some potential to differentiate into trophoblast derivatives. Here, we show that ELF5 is expressed in the human placenta in villous cytotrophoblast cells but not in post-mitotic syncytiotrophoblast and invasive extravillous cytotrophoblast cells. ELF5 establishes a circuit of mutually interacting transcription factors with CDX2 and EOMES, and the highly proliferative ELF5(+)/CDX2(+) double-positive subset of cytotrophoblast cells demarcates a putative TS cell compartment in the early human placenta. In contrast to placental trophoblast, however, ELF5 is hypermethylated and largely repressed in human ES cells and derived trophoblast cell lines, as well as in induced pluripotent stem cells and murine epiblast stem cells. Thus, these cells exhibit an embryonic lineage-specific epigenetic signature and do not undergo an epigenetic reprogramming to reflect the trophoblast lineage at key loci such as ELF5. Our identification of the trophoblast-specific transcriptional circuit established by ELF5 will be instrumental to derive human TS cell lines that truly reflect early placental trophoblast and that will be most beneficial to gain insights into the aetiology of common pregnancy complications, including intra-uterine growth restriction and pre-eclampsia.